Path: utzoo!yunexus!geac!daveb
From: daveb@geac.UUCP (David Collier-Brown)
Newsgroups: comp.databases
Subject: Re: Informix 4GL Question?
Summary: well, a wee bit broader than that...
Keywords: Informix 4GL
Message-ID: <2314@geac.UUCP>
Date: 22 Feb 88 18:35:31 GMT
Article-I.D.: geac.2314
Posted: Mon Feb 22 13:35:31 1988
References: <714@uel.uel.co.uk>
Reply-To: daveb@geac.UUCP (David Collier-Brown)
Organization: The Geac Thimktank :-}
Lines: 32

In article <714@uel.uel.co.uk> andrew@uel.uel.co.uk (Andrew Josey) writes:
>When deleting records in my database I check whether they are
>referenced by any other records. This is currently done by code
>similar to the following :
>
>let counter = 0
>select count (*) into counter from table
>  where table.column = key
>if counter > 0
>...
>As some of my database tables are large, I would like to find
>an alternative technique that terminates after finding the first
>match instead of searching the whole table.

   This is interesting, in that it is a perfectly plausible request
that does not **seem** to be well-defined in the relational
algebra/calculus (and perhaps even less well-defined in the *#%!@?&&
sublanguages we get with them).

   Can someone with a deeper knowledge of relational theory comment
on this, especially with respect to saying
	1) "give me one of"  -- the current problem
	2) "give me the first n of" -- from a problem in bibliographic
					search
	3) "give me any n of"

 --dave (this exists for a reason. I wonder what it is) c-b
-- 
 David Collier-Brown.                 {mnetor yunexus utgpu}!geac!daveb
 Geac Computers International Inc.,   |  Computer Science loses its
 350 Steelcase Road,Markham, Ontario, |  memory (if not its mind) 
 CANADA, L3R 1B3 (416) 475-0525 x3279 |  every 6 months.